Accession Number : AD0618160

Title :   CINNAMIC ACID HYDROXYLASE IN SPINACH,

Corporate Author : NATIONAL RESEARCH COUNCIL OF CANADA HALIFAX (NOVA SCOTIA) ATLANTIC REGIONAL LAB

Personal Author(s) : Nair,P. M. ; Vining,L. C.

Report Date : 21 MAY 1964

Pagination or Media Count : 9

Abstract : An acetone precipitate from an extract of spinach leaves catalysed the hydroxylation of trans-cinnamic acid to p-coumaric acid. The enzyme was unstable and could not be purified. Crude preparations had a pH optimum of 4.6 and showed an absolute requirement for an external electron donor. Tetrahydrofolic acid and a reduced pyridine nucleotide coenzyme were necessary for maximum activity. Aminopterin was a potent inhibitor of the hydroxylating system. No requirement for metal ions could be demonstrated but inhibition by p-chloromercuribenzoate suggests that a sulfhydryl group participates in the reaction. These properties, and the course of the reaction when cofactors were added separately, indicate a similarity between this enzyme and the phenylalanine hydroxylase of mammalian liver. The crude spinach preparation also catalysed and the conversion of L-phenylalanine to tyrosine, and addition of L-phenylalanine inhibited cinnamic acid hydroxylase activity. (Author)

Descriptors :   (*PLANTS(BOTANY), ENZYMES), (*ENZYMES, PLANTS(BOTANY)), COENZYMES, INHIBITION, CATALYSIS, PHENYLALANINE, TYROSINE, CANADA

Distribution Statement : APPROVED FOR PUBLIC RELEASE